You can go wading in the lake at the North Pole

Last week, Dean told you about the lake at the North Pole, a pool of melted ice captured on camera by the North Pole Environmental Observatory webcams.

At Climate Central, Andrew Freedman provides some really fascinating context that illustrates the changing nature of, well, nature ... and draws a big, heavy underline on how difficult it can be to make assumptions about what is and what isn't an effect of climate change. Arctic sea ice is melting in concert with rising global average temperatures, but (contrary to the knee-jerk assumption I made about this story) the lake at the North Pole may or may not have anything to do with that. In fact, little pools have been forming at the North Pole in summer for as long as we've been paying attention. They don't actually represent the total melting of ice, but rather a layer of slushy water that forms on top of solidly frozen ice — usually, you could wade out through them and never get more than waist-deep.

What's more, the picture above wasn't taken at the North Pole. That's because the North Pole Elemental Observatory — which sits on mobile ice — has moved far from the actual North Pole since its launch. So, there probably is a lake (more of a pond, really) at the North Pole, but it might not be caused by climate change. While this lake, which isn't at the North Pole, could well be part of the melting sea ice that climate change does cause. But it also might not, because what happens as a result of climate change is always layered on top of stuff that just happens. In order to be able to tell the difference, you have to do a lot of scientific analysis — much more than you can get from one picture.

For instance, here's a photo taken by the North Pole Elemental Observatory today. The fact that there isn't a pond there now doesn't prove climate change isn't happening — any more than the presence of a pond proves it does. What it does show you is that there is normal variation in what nature looks like and the job of climate scientists is to tease apart the normal variation from the stuff that's man-made.